Abstract (Excerpt)

In order to trigger an adaptive immune response, T cells move
through lymph nodes searching for dendritic cells that carry
antigens indicative of infection. We observe T cell movement
in lymph nodes and implement those movement patterns as a
search strategy in a team of simulated robots. We find that the
distribution of step-sizes taken by T cells are best described
by heavy-tailed (Lévy-like) distributions. Such distributions
are characterized by many small steps and rare large steps.
Our simulations show that heavy-tailed motion leads to dramatically
faster search compared to Brownian motion, both
in groups of T cells and in teams of robots. The mechanisms
that cause heavy-tailed movement patterns in T cells are not
fully understood. However, in robot simulations we find that
heavy-tailed movement improves search speed whether that
movement is caused by rules intrinsic to the robots or by
adaptive response to extrinsic factors in the environment.